Here is a patch to implement "Support triggers on columns" in our ToDo list.
The syntax is:
CREATE TRIGGER name
BEFORE UPDATE OF col1, col12, ...
ON tbl FOR EACH ROW EXECUTE PROCEDURE func();
I consulted the previous work following:
Column-level triggers (From: Greg Sabino Mullane, Date: 2005-07-04)
http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
and completed some under-construction parts.
It's still arguable that we should add dependencies from column
triggers to referenced columns. In the present patch, dropeed
columns are just ignored and always considered as not-modified.
Please grep with "TODO: (TRIGGER)" to check the issue.
Comments welcome.
Regards,
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ITAGAKI Takahiro
NTT Open Source Software Center